This invention relates to novel liquid crystal substances which exhibit a liquid crystal phase within broad temperature ranges and have lower viscosities.
Liquid crystal display elements utilize optical anisotropy and dielectric anisotropy of liquid crystal substances, and are classified into various types such as TN type (twisted nematic type), DS type (dynamic scattering type), guest-host type, DAP type, etc. according to their display modes, and the properties of liquid crystal substances suitable to their respective uses are different. However, it is common to any liquid crystals that stabilities to moisture, air, heat, light, etc. are required, and it is also necessary that they exhibit a liquid crystal phase within as broad a temperature range as possible, around room temperature, and further, have an optimal value of dielectric anisotropy (.DELTA..epsilon.) varied depending on the kinds of display elements. At present, however, no single compound which alone satisfies such conditions is present, and it is the present status that a liquid crystal composition obtained by blending several kinds of liquid crystal compounds or non-liquid-crystal compounds is used. Recently, display elements actuating over from lower temperatures (about -20.degree. C.) up to higher temperatures (about 80.degree.-90.degree. C.) have been particularly needed; thus, liquid crystal compositions having superior actuation characteristics within a broader temperature range have been desired.
The object of the present invention is to provide novel liquid crystal compounds which are useful as a component of such liquid crystal compositions and particularly suitable to improvement in low temperature characteristics.